The Homeland Security Department has decided that a technology-heavy approach to controlling the northern border would be less disruptive to the environment than adding patrol stations, fencing or other infrastructure. Still, this preferred choice would entail more than 400 construction projects and risk harming historic sites, according to a new 1,200-page internal assessment.

The evaluation of strategy options, called a programmatic environmental impact statement, is required by law for any government activity that would significantly influence the quality of ecological conditions. The study is a planning tool, DHS Customs and Border Protection officials said, in releasing the rationale for the potential tech-centric strategy on Friday.

The approach “could become required within the next five to seven years in response to yet unknown changes in threat conditions along the 4,000-mile border with Canada stretching from Maine to Washington State,” officials stated. “Deployment of towers and radar to new emplacements would potentially change the visual landscape of the northern border somewhat, but in ways that might be more easily mitigated relative to the other action alternatives.”

The plan requires fielding mobile video surveillance systems, short-range radar, ground sensors, drones and a slew of other inspection tools to intercept people involved in cross-border crimes. The upgrades are intended to save time and money by ascertaining where the risk of illegal incursions is greatest so that officers and equipment can be positioned accordingly.

“Technology enhancements to facilitate scanning and screening of personnel and goods at [entry points] would expedite CBP’s ability to facilitate legitimate cross boundary trade and travel . . . while avoiding the more prominent delays associated with rerouting traffic and closing lanes to accommodate construction to increase lane numbers or size on existing facilities,” the evaluation states.

While less invasive than concrete-intensive strategies, the approach would require some additional infrastructure at many spots such as poles, towers and access roads for maintenance, according to officials.

The option “increases the potential for long-term, adverse impacts due to the need to site the structures in a wide variety of locations, some of which may be the location of cultural and paleontological resources or within the view shed of Native American cultural resources,” the assessment acknowledges.

A preliminary study apparently sparked backlash among some affected individuals, communities and organizations, based on their published comments.

Federal officials stressed they will carry out separate environmental analyses for each project. The study does not predict the impact on specific landmarks or regions. “Any CBP proposals for projects or activities at specific locations would be made in the future and would comply with all applicable statutory and regulatory environmental requirements,” the plan states. At that time, officials will consult with local land owners and tribes, in coordination with preservation agencies.

The initial assessment presented constituents with hundreds of pages detailing geographical features that would be affected by any of the strategic options. The public then was given an opportunity to correct the record and respond to the assessment. Comments came in from federal agencies, state and local governments, conservation bodies, tribes, wildlife societies and various advocacy organizations.

An unidentified entity noted that adjustments to the Peace Bridge crossing in Buffalo, N.Y., could affect national protected land where the bridge operates, as well as the adjacent Prospect Hill-Columbus Park historic district.

Another observer expressed concern about Native American tribal territory intersected by the international border with the Saint Lawrence River: “At Akwesasne, the border passes through residential areas, gov facility parking lots, a radio station, and sensitive environmental features such as forests, wetlands, and rivers. . . The border area is rich with archaeological features dating back thousands of years and all must be considered in any enhancements to the existing border enforcement program.” The person urged government officials to consult extensively with tribal leaders and community members when they are ready to move forward.

The evaluation “incorrectly summarizes the primary purpose of the High Ross Treaty, which resolved a long-standing international environmental dispute by stating that, at least until 2065, the Ross damn would not be raised,” pointed out Scott Powell of the Skagit Environmental Endowment Commission.

Officials subsequently changed the final plan to elaborate on the commitments of the 1984 treaty, including the fact that Powell’s commission was established “to enhance recreational opportunities and to conserve and protect wilderness and fish and wildlife habitat in the Upper Skagit Watershed until 2065 through mechanisms such as acquisition of timber and mineral rights and execution of projects such as trail system development.”

The assessment does not identify participants whose comments were not incorporated into the final report.

The agreed-to strategy likely would require deploying more military engineering teams or private contractors to install infrastructure for the new equipment, according to officials. They also would be needed to maintain underground sensors.

New technology undergoing testing would link ground sensors with surveillance cameras using wireless networks to better detect low-flying, drug-smuggling aircraft that often evade agents. Truck-mounted imaging systems could be used for inspecting unmovable cargo such as railroad cars. And portable solar power panels may run some communications equipment.

Relying more on computers actually could benefit some historic sites, the report notes. For example, projects could be designed to rehabilitate historic properties. CBP officials said, whenever possible, they intend to piggyback off existing government equipment instead of adding infrastructure. For instance, there already is a plan to position enhancements for one CBP radio communications system with the Maine State Police and to use existing towers where practicable.

The study adds that expanded use of unmanned aircraft, such as the Predator drone, “would translate into negligible (not distinguishable from existing) changes in the overall noise environment” because the systems generally are quieter, operate at much higher altitudes and are used less frequently than helicopters.